See explanation below
Explanation
1. Open Microsoft Azure Portal
2. Log into your Azure account and go to App Service and look under Monitoring then you will see Alert.
3. Select Add an alert rule
4. Configure the alert rule as per below and click Ok.
Source: Alert on Metrics
Resource Group: az400-9940427-main
Resource: az400-9940427-main
Threshold: 5
Period: Over the last 5 minutes
Webhook: https://contoso.com/notify
Graphical user interface, text, application Description automatically generated

Reference:
https://azure.microsoft.com/es-es/blog/webhooks-for-azure-alerts/